The present invention relates to a probe card for testing semiconductor wafers and, more specifically, to a modularized probe card with coaxial transmitters.
After fabrication, semiconductor devices will need to pass functional test to verify their electrical performance within design specification. The test apparatus for chip probing usually comprises a probe card with a plurality of probe needles for contacting with electrodes, such as bond pads or bumps, of a wafer.
A conventional improved probe card mainly comprises a substrate with a top and a bottom side. Both sides of the substrate are formed with a large ground plane and a plurality of contact points, wherein the ground plane is soldering with outer shields of coaxial cables to provide ground and shielding. The contact points provide electrical connections with a tester. The top side of the substrate is formed with a plurality of soldering points to solder a plurality of probe needles. A plurality of coaxial cables provide electrical connections between probe soldering points and contact points. The coaxial cable provides electrical connection respectively, therefore, it not only acquires more time in manufacturing rectangular probe card, but also comes up with the problem of improper connections or miss wiring between coaxial cables.
Furthermore, in U.S. Pat. No. 4,731,577 entitled xe2x80x9cCOAXIAL PROBE CARDxe2x80x9d, a multipoint microwave coaxial probe card is disclosed. A printed circuit board has edge connectors and a mounting ring attached to the surface. The mounting ring has a plurality of holes, and each is assembled with a microwave connector. These microwave connectors electrically connect to probe needles by coaxial cables. A portion of the probe needles are joined to the edge connector by insulated wires allowing both high and low frequency signals to be utilized simultaneously. Furthermore, a shield in the form of a flat plate, with a cover, encloses the ring and provides RFI and EMI shielding, and allows the coaxial probe card to test the microwave semiconductor wafers. However, non-modularized coaxial probe card is not easily to be detached and assembled, and therefore it is difficult to repair once malfunction occurs.
A main purpose of the present invention is to supply a modularized probe card with coaxial transmitters. At least a coaxial transmitter is modularized and installed between a first printed circuit board and a second printed circuit board. When it requires to test another semiconductor devices with same electrical function yet different pad distribution, the whole probe card can be reused except the probe head. A new probe head corresponding to the semiconductor devices manufactured and assembled to the second printed circuit board to save the cost of manufacturing a new probe card.
A second purpose of the present invention is to supply a modularized probe card with coaxial transmitters with both ends of each coaxial cable connecting to plug-in and pull-away type connectors. These connectors are used to collect and fasten coaxial cables of coaxial transmitters, and to electrically connect with the first and second printed circuit boards. This will eliminate the problem of improper connections for individual coaxial cables, and reduce the assembly time of a probe card.
A third purpose of the present invention is to supply a modularized probe card with coaxial transmitters installing at least a coaxial cable. The coaxial cable is easily to be replaced with new one and thus to ensure that coaxial cable is always in good electrical function. Furthermore, miss wiring could be eliminated and it is easy to repair the probe card once malfunction occurs.
The modularized probe card with coaxial transmitters according to the present invention comprises at least a coaxial transmitter, a first printed circuit board, a second printed circuit board, and a probe head. Wherein the coaxial transmitter is composed of a first connector, a second connector and a plurality of coaxial cables. It is modularized and installed between the first and the second printed circuit board, as a transmitting route for probing wafers. One ends of the coaxial cables are connected to the first connector, and correspondingly connected to the first connecting devices of first printed circuit board. The other ends of the coaxial cables are connected to the second connector, and correspondingly connected to the second connecting devices of second printed circuit board in a plug-in and pull-away type. The probe head is mounted and electrically connected to the second printed circuit board, and forming with a plurality of probes for contacting semiconductor wafers.